Explaining Medical Model Exceptions - Computational Intelligence in Healthcare: Advanced Methodologies - page 257

1. Construct a model,
2. Point out the exceptions,
3. Find causes why the exceptional cases do not fit the model, and
4. Set up a case base.
So, Case-Based Reasoning is combined with a model, in this specific situation with a
statistical one. The idea to combine CBR with other methods is not new. Care-
Partner, for example, resorts to a multi-modal reasoning framework for the co-
operation of CBR and rule-based reasoning (RBR) [17]. Montani et al. [18] rather use
CBR to provide evidences for a hybrid system in the domain of diabetes. Another
way of combining hybrid rule bases with CBR is discussed by Prentzas and Hat-
zilgeroudis [19]. The combination of CBR and model-based reasoning is discussed in
[20]. However, statistical methods are used within CBR mainly for retrieval and re-
tention [21,22]. Arshadi and Jurisica [23] propose a method that combines CBR with
statistical methods like clustering and logistic regression.
The first application of ISOR is on hemodialysis and fitness. Unfortunately, the
data set contains many missing data, which makes the process of finding explanations
for exceptional cases difficult. So, we decided to attempt to first solve the missing
data problem. This is done by partly applying CBR again.
2 Incremental Development of an Explanation Model for
Exceptional Dialysis Patients
Hemodialysis means stress for a patient's organism and has significant adverse ef-
fects. Fitness is the most available and a relative cheap way of support. It is meant to
improve a physiological condition of a patient and to compensate negative dialysis
effects. One of the intended goals of this research is to convince patients of the posi-
tive effects of fitness and to encourage them to make efforts and to actively partici-
pate in the fitness program. This is important because dialysis patients usually feel
sick, they are physically weak, and they do not want any additional physical load [24].
At the University clinic in St. Petersburg, a specially developed complex of physio-
therapy exercises including simulators, walking, swimming, and so on is offered to all
dialysis patients but only some of them actively participate, whereas some others par-
ticipate but are not really active. The purpose of this fitness offer is to improve the
physical conditions of the patients and to increase the quality of their lives. The hy-
pothesis is that actively participating in the fitness program improves the physical
condition of dialysis patients.
For each patient a set of physiological parameters is measured. These parameters
contain information about burned calories, maximal power achieved by the patient,
oxygen uptake, oxygen pulse (volume of oxygen consumption per heart beat), lung
ventilation, and others. There are also biochemical parameters like haemoglobin and
other laboratory measurements. More than 100 parameters were planned for every
patient. But not all of them were actually measured.
Parameters are supposed to be measured four times during the first year of partici-
pating in the fitness program. There is an initial measurement followed by one after